Interesting to note that a little over 1 year ago I could not do DB presses too well and they would aggravate my shoulders/chest, I think it was because I was also doing them inclined. I avoid incline pressing and am still increasing reps with the 70's and shoulders feel well (at the moment)

Hack squat is only whole leg exercise that does not hurt my back. Must use light weight for now on.

The hack machine you rest on back at about 60 degrees supporting the weight /sled assembly with your feet placed stationary on a platform. There is no pressure or load on my back when I use this, unlike the leg press or squat.